Besides applications, wherein classical activated carbons are used as a mass product, applications requiring special high-performance activated carbons are becoming increasingly important. These are applications, wherein the required amounts of activated carbon for a certain purpose and a certain time of use have to be kept low, and nevertheless excellent adsorption properties (adsorption kinetics, capacity) are required. These are in particular mobile applications, such as for filters in vehicles (cars, aircrafts, etc.) or in gas masks, but also in building air filters. Besides a favorable capacity/weight ratio, other requirements also play a role, such as a low pressure loss over a filter containing the activated carbon. This also means, however, that it is not always possible for in so far additional requirements to use activated carbons maximized with regard to the BET surface; rather, it may be necessary to use activated carbons, which in spite of a moderate BET surface have nevertheless outstanding adsorption properties. In any case, excellent adsorption properties are required, in particular in the case of filters, which are intended to protect persons from toxic gases. In addition, it is desired that a spherical activated carbon is particularly abrasion resistant.
From the document EP 0 326 271, a method for producing an activated carbon is known in the art, which can be prepared from a polysulfonated copolymer. The obtained activated carbon has a multimodal pore size distribution, i.e. a high share of mesopores and macropores.
From the document WO 96/21616, a method for producing an activated carbon from monosulfonated copolymers is known in the art.
From the document WO 99/28234, a method for producing an activated carbon from styrenedivinylbenzene copolymers is known in the art, and by variation of parameters of the method, the pore size distribution can be adjusted in a wide range.
From the document U.S. Pat. No. 4,957,897, a method for producing an activated carbon from a polysulfonated vinylaromatic copolymer is known in the art, wherein the carbonization is effected under dissociation of sulfonic acid groups.
From the document WO 2004/046033, a spherical activated carbon is known in the art, which has an improved pore size distribution.
The educt often used in the above methods is a fresh or spent ion exchanger of a spherical shape. This is a (co)polymer, which carries chemically active groups, for instance sulfonic groups, and has a porous structure or a gel structure. The man skilled in the art knows such ion exchangers from the practice.
All above prior art methods for the production of activated carbons have the common drawback that the absorption properties and the abrasion resistance do not yet meet the highest requirements. In particular the individual grain load can also be improved.